Or XXX::Simple? CGI::Simple has reduced functionality of the parent, sans HTML output, amoung other things. And, I believe, it's not built on top of the parent either but a complete rewrite. So in this context, "subclass" is quite a broad definition.
I use a couple of old versions of modules (DBM::Deep, CGI::Session) because "recent" versions include XS dependancies which aren't currently available (negotiations with webhosters pending). Far from ideal; better would be Lite or Simple versions that were maintained.